ruxolitinib phosphate (RUK-soh-LIH-tih-nib FOS-fayt)
A drug used to treat certain types of myelofibrosis. It is also being studied in the treatment of other blood diseases and some types of cancer. Ruxolitinib phosphate blocks a protein called JAK, which may help keep abnormal blood cells or cancer cells from growing. It is a type of tyrosine kinase inhibitor. Also called Jakafi.